1. Field of the Invention
This invention relates to a tubular core that can be used for winding tape, yarn, and the like and, more particularly, to a spirally-wound tubular core that includes at least one polymer ply.
2. Description of Related Art
Tubular cores are typically used for supporting wound lengths of tape, yarn, paper, and the like. Such cores are found in products intended for consumer use, medical applications, manufacturing, and the like. For example, tubular cores are often used to wind adhesive tape and support the resulting roll of tape in a dispenser. One conventional tubular core for adhesive tape is formed by spirally winding a paper ply on a mandrel to form a paper tube. Multiple paper plies can be layered on the mandrel with an adhesive disposed therebetween so that the resulting tube is stiff. The tube is then cut to form a number of tubular cores, each having a desired length. Additionally, the innermost paper ply can be printed before winding, for example, with text, other indicia, or colors to indicate the tape manufacturer, the type of tape, and the like.
Although widely used, such paper cores are inappropriate or unacceptable for certain applications. For example, tape for medical and clean manufacturing applications is used in controlled environments where the production of dust associated with the paper cores is undesirable. The paper cores are also generally not clean enough for use in controlled medical environments. In addition, the paper cores tend to lack dimensional stability, especially when stressed or subjected to moisture and temperature variations. Changes in the size of the cores can complicate the winding process, for example, where multiple paper cores are adjacently positioned on a shaft and rotated in unison to wind a ribbon of tape on each core. Changes and dissimilarities in the length of the cores can result in some of the ribbons of tape being wound partially onto more than one core, i.e., two adjacent cores, such that the adjacent cores cannot be separated after winding. The paper cores can also weaken if subjected to moisture after winding. Thus, yarn or other products wound on the cores can result in a radially compressive load that exceeds the strength of the weakened cores, thereby causing the cores to collapse. Further, many adhesives used for tapes adhere to the paper cores. When the innermost end of the tape is removed from the core, paper fibers are lifted from the core by the tape. Thus, the end of the tape is generally unusable, and the removal of the tape from the core can make dust that is unacceptable in some environments.
Extruded or injection-molded plastic cores are sometimes used instead of paper rolls, for example, for adhesive tapes. Plastic cores can be clean and are typically dust free, even when the tape is completely removed from the core. In addition, plastic cores are generally dimensionally stable throughout a range of temperatures and moistures. However, some cores can be difficult to form to precise dimensions by extrusion and injection molding, especially larger cores such as those with an inner diameter of about 3 inches or more. Moreover, printing on the inside of the plastic cores can be difficult.
Thus, there exists a need for a tubular core that can be used to support wound products such as tape, yarn, paper, and the like. The core should be compatible with conventional printing methods so that indicia or colors can be provided thereon. Preferably, the core should be dimensionally stable when subjected to moisture or other environmental changes. Further, the core should allow the removal of the wound product without generating unacceptable dust or other debris.